XSLT Reference
xsl:output
Controls how the result tree is serialised — output method, encoding, indentation, DOCTYPE, and other serialisation options.
Syntax
<xsl:output method="xml|html|text" indent="yes|no" encoding="UTF-8"/>Description
xsl:output is a top-level declaration that controls the serialisation of the result tree — how the abstract tree of nodes is converted to a stream of characters or bytes. It does not affect what nodes are in the result tree; it only affects how those nodes are written to the output.
The three standard output methods are:
xml— Serialises as an XML document. Special characters are escaped, an XML declaration may be added, and the result is always well-formed XML.html— Serialises following HTML conventions: void elements like<br>are written without a closing tag, boolean attributes are written without values, and theDOCTYPEis added if specified.text— Serialises only the string values of text nodes; all markup is omitted.
Multiple xsl:output declarations in the same stylesheet are allowed and their attributes are merged. When the same attribute appears in multiple declarations, the one with the highest import precedence wins; within the same precedence level, the last declaration wins.
Attributes
| Attribute | Type | Required | Description |
|---|---|---|---|
method | xml / html / text / QName | No | Serialisation method. Default is xml unless the root element is html. |
version | NMTOKEN | No | Version of the output format (e.g., "4.0" for HTML). |
encoding | encoding name | No | Character encoding (e.g., "UTF-8", "ISO-8859-1"). |
omit-xml-declaration | yes / no | No | Whether to suppress the <?xml ...?> declaration. |
standalone | yes / no | No | Value of the standalone attribute in the XML declaration. |
doctype-public | string | No | Public identifier for the DOCTYPE declaration. |
doctype-system | string | No | System identifier for the DOCTYPE declaration. |
cdata-section-elements | whitespace-separated QNames | No | Elements whose text content should be serialised as CDATA sections. |
indent | yes / no | No | Whether to add whitespace indentation. |
media-type | MIME type | No | Media type of the output. |
Examples
XML output with indentation
Input XML:
<?xml version="1.0" encoding="UTF-8"?>
<data><item>A</item><item>B</item></data>
Stylesheet:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" indent="yes" encoding="UTF-8"/>
<xsl:template match="@*|node()">
<xsl:copy>
<xsl:apply-templates select="@*|node()"/>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
Output:
<?xml version="1.0" encoding="UTF-8"?>
<data>
<item>A</item>
<item>B</item>
</data>
HTML output with DOCTYPE
Input XML:
<?xml version="1.0" encoding="UTF-8"?>
<page><title>Hello</title><body>World</body></page>
Stylesheet:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="html" indent="yes" encoding="UTF-8"
doctype-public="-//W3C//DTD HTML 4.01 Transitional//EN"
doctype-system="http://www.w3.org/TR/html4/loose.dtd"/>
<xsl:template match="/page">
<html>
<head><title><xsl:value-of select="title"/></title></head>
<body><p><xsl:value-of select="body"/></p></body>
</html>
</xsl:template>
</xsl:stylesheet>
Output:
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head><title>Hello</title></head>
<body><p>World</p></body>
</html>
Notes
xsl:outputis advisory: a processor is not required to serialise the result at all (it may hand the result tree to a further processing step). When serialisation does occur, the processor should honour the settings.indent="yes"may add whitespace-only text nodes to the output. This can cause problems if the consuming application is whitespace-sensitive; use it only for human-readable output.cdata-section-elementsis useful for elements containing JavaScript or CSS in HTML, where<,>, and&should not be escaped.- In XSLT 2.0+,
xsl:outputgains additional attributes includinguse-character-maps,normalization-form,undeclare-prefixes, andhtml-version.